The present invention relates to the field of hair treatment and particularly to the removal of chemically bound residues and mineral deposits from hair. Hair may act as a sink for environmental minerals and heavy metals. In addition to undesirable changes in color and appearance, environmental minerals may have an adverse effect on chemical hair treatments. Mineral deposits in tap water may strip away highlights, darkening hair color to a brassier hue.
The phenomenon of blonde hair acquiring a green tint when exposed to swimming pool water containing copper has been attributed to copper mineral absorption by hair. Such absorption occurs when copper is in the form of a weak complex of copper sulfate. Subsequent shampooing with a conventional composition cannot strip the green color. (Reference. G. Ramachandra Bhat, et. al., J.Soc. Cosmet. Chem., 30, 1-8 (January/February 1979).
Previous attempts to develop compositions for the removal of minerals from human hair have utilized high concentrations of known chelating agents, extended contact times and processes which require the application of heat. In addition, special packaging may be required to prevent decomposition in the presence of air. For example, Ault in U.S. Pat. No. 5,804,172 issued Sep. 8, 1998 discloses a composition for use in removal of minerals from hair which comprises the combination of an acidifying agent, a reducing agent, a chelating agent, a gelling agent and water. A synergistic combination of chelating agents is stated to be disclosed in the Ault patent. Also disclosed in the Ault patent is a process for packaging the compositions and a method for removal of mineral residues from hair by the use of such compositions. The method disclosed in the Ault patent for the removal of mineral residues from hair may take up to 45 minutes for the removal of iron from hair. It is also stated in the Ault patent that the process requires the application of heat and an airtight container to prevent oxidation that would negate the usefulness of the invention.
U.S. Pat. No. 5,635,167 to Said, et al., issued Jun. 3, 1997 discloses a process for the removal of exogenous metal ions attached to human hair or keratin fiber which include the steps of contacting at least one chelating agent to the human hair or keratin fiber, the chelating agent selected from the group consisting of amino acid-type, polyphosphate-type and phosphonate-type agents, maintaining contact with the chelating agent and the human hair or keratin fiber for a period of time sufficient to permit the chelating agent to complex with the exogenous minerals, thereby removing at least a portion of the attached minerals, and rinsing the chelating agent.
The process of the Said, et al., patent is enhanced with the pH adjusted to a range of between 4 to 9, preferably 5 to 8. The chelating agent of the Said, et al., patent is added at a concentration of 4% by weight to 25% by weight, preferably 5 to 20% by weight. In a preferred case, the chelating agent is selected from the group consisting of a salt of ethylenediamine-tetraacetic acid, a salt of hydroxyethylethylenediaminetriacetic acid, a salt of diethylenetriaminepentaacetic acid, a salt of nitrilotriacetic acid and a salt of tripolyphosphate, preferably the sodium salt.
The Said, et al., patent teaches high concentrations of polyphosphate or phosphonate which may be irritating to the scalp of certain sensitive individuals and may limit the utility of the proposed invention for use in low irritation shampoo compositions.
Gary, et al., in U.S. Pat. No. 3,998,761 issued Dec. 21, 1976 discloses a shampoo composition suitable for conditioning hair. The compositions of the Gary, et al., patent comprise at least one detergent and a waste liquid beer sludge concentrate distributed in an aqueous medium. The beer solids are stated to be, in the Gary, et al., patent composition at from about 4% to 20% by weight based on the total weight of the shampoo composition and wherein said detergent comprises about 10 to 20% based on the total weight of the composition. The compositions of the Gary, et al., patent may contain minor amounts of proteins.
U.S. Pat. No. 4,581,229 issued to Petrow on Apr. 8, 1986 discloses a hair treating solution and method which is stated to provide for improving hair quality and aiding in removal of inorganic substances from hair. The Petrow patent states that metals such as copper, iron, manganese, nickel and the like, if attached to hair after swimming or other hair-exposure thereto, can be removed by the use of a soluble lanthanum salt in a simple rinsing method.
The coloring of hair to a desired shade and having the hair retain the desired shade is quite important to consumers as set out in U.S. Pat. No. 5,112,359 Murphy, et al., issued May 12, 1992. The Murphy, et al., patent discloses certain dispersant free substituted diaminoanthaquinone (sic) colorants stated to be useful in hair dye compositions to more intensely color hair. The Murphy, et al., patent states that coloring kits, mousses, gels, and aerosols may contain the compositions disclosed therein.
Cationic polymers are used in shampoos and conditioners to facilitate combability and to make the hair feel softer and smoother to the touch. Cationic surfactants are positively charged molecules that have an affinity for negatively charged sites on the hair. When used repeatedly, an excess of cationic polymer may buildup on the hair shaft, resulting in dull, lifeless hair. Compositions for the removal of minerals from human hair do not address the problem of cationic polymeric buildup on the hair shaft.
U.S. Pat. No. 4,412,026 issued to Collins Oct. 25, 1983 discusses polymeric compositions, and in particular, the homopolymeric salt of 2-acrylamido-2-methylpropanesulfonic acid in an amount to sufficient to thicken the compositions disclosed therein.
Throughout the specification and claims, percentages and ratios are by weight, and temperatures are in degrees Celsius unless otherwise indicated. To the extent that any of the references cited herein are applicable, they are hereby specifically incorporated by reference. Ranges and ratios given herein may be combined.
The present invention describes a composition suitable for removing deposits from hair comprising:
(a) an amino acetic acid;
(b) a member selected from the group consisting of a salt of ethylenediaminetetraacetic acid, a salt of hydroxyethylethylenediaminetriacetic acid, and a salt of diethylenetriaminepentaacetic acid, and mixtures thereof;
(c) citric acid; and,
(d) water.
A further aspect of the present invention is a composition which is the reaction product of a mixture comprising:
(a) glycine;
(b) a member selected from the group consisting of a salt of ethylenediaminetetraacetic acid, a salt of hydroxyethylethylenediaminetriacetic acid, and a salt of diethylenetriaminepentaacetic acid, and mixtures thereof;
(c) citric acid; and,
(d) water.
Yet a further aspect of the present invention is a method for removing chemically bound residues and/or mineral deposits from hair upon the head by applying a sufficient amount of a composition comprising:
(a) an amino acetic acid;
(b) a member selected from the group consisting of a salt of ethylenediaminetetraacetic acid, a salt of hydroxyethylethylenediaminetriacetic acid, and a salt of diethylenetriaminepentaacetic acid, and mixtures thereof;
(c) citric acid; and,
(d) water;
for a sufficient time to remove residues and/or mineral deposits from hair upon the head.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the preferred embodiment. No limitation of the scope of the invention is thereby intended for further applications of the principles of the invention, which would normally occur or be contemplated by one skilled in the art to which the invention relates.
One aspect of the present invention relates to a composition and method for removing chemically bound minerals from hair comprising a multidentate ligand complex and water in a weakly alkaline environment. The complex is formed by adding glycine to an alkaline solution of a member selected from the group consisting of a salt of ethylenediaminetetraacetic acid, a salt of hydroxyethylethylenediaminetriacetic acid, and a salt of diethylenetriaminepentaacetic acid, and mixtures thereof. Preferably, the salt is the tetrasodium salt of ethylenediaminetetraacetic acid (EDTA) followed by the addition of citric acid to a weakly alkaline pH of approximately 7.5. The resultant xe2x80x9ccitrified glycine edetatexe2x80x9d composition has been found to be highly effective in removing bound environmental minerals by a unique hair penetration and chelation process.
It is understood that while citric acid is the preferred ingredient, that any material capable of generating citric acid is included within the definition of citric acid. Thus, citrate salts such as sodium citrate may be employed herein.
Chelation is a chemical reaction or process involving chelate ring formation and is characterized by multiple bonding between two or more of the electron-pair-donor groups of a multidentate ligand and electron-pair-acceptor metal ion.
It is an object of the present invention to provide a synergistic composition suitable for removing minerals from hair, which includes the tetrasodium salt of amino acetic acid (glycine), and the tetrasodium salt of ethylenediaminetetraacetic acid neutralized to a weakly alkaline pH with citric acid.
It is another object of the present invention to provide a process for simultaneously removing minerals and cationic surfactant and/or polymer buildup with a composition containing the tetrasodium salt of amino acetic acid and the tetrasodium salt of ethylenediaminetetraacetic acid neutralized to a weakly alkaline pH with an anionic polymer such as polyacrylamidomethylpropane sulfonic acid. It is theorized that the sulfonic acid portion of the polymer molecule and amino acetic acid forms hydrogen bonds with the tetrasodium salt of ethylenediaminetetraacetic acid forming a polyglycine edetate complex.
Hair is an assembly of fibers that contain proteins, which may bind minerals by both ionic bonds and covalent bonds. Cationic surfactants and polymers are positively charged molecules, which have an affinity for negatively charged sites on the hair. Undesirable buildup on hair fiber surfaces may result when certain types of cationic surfactants and polymers are used repeatedly to condition the hair.
The inventive compositions include three ingredients: aminoacetic acid (glycine), a member selected from the group consisting of a salt of ethylenediaminetetraacetic acid, a salt of hydroxyethylethylenediaminetriacetic acid, and a salt of diethylenetriaminepentaacetic acid, and mixtures thereof; and citric acid at a weakly alkaline pH. The resultant xe2x80x9ccitrified sodium glycinate edetatexe2x80x9d complex appears to be capable of penetrating into the peripheral region of the hair fiber where absorbed minerals, such as copper, are primarily located. The weakly alkaline environment is advantageous to the promotion of cuticle swelling, thereby enhancing penetration of the chelating complex.
The inventive composition is preferably applied to the hair as a spray followed by shampooing for mineral removal. An alternative approach is to incorporate the glycinated chelating complex directly into a shampoo or hair conditioner for mineral removal. When an anionic polysulfonate salt is included in cleansing compositions containing the glycinated-chelating complex, the removal of undesirable buildup on hair fiber surfaces is also facilitated.